Sprocket



FIG. 1 is a rear elevation view of the sprocket embodying our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a side elevation view thereof; and

FIG. 4 is a fragmentary sectional view thereof taken on line 4--4 of FIG. 2. 

The ornamental design for a sprocket, as shown. 